The use of hygroscopic, deliquescent materials as sorption means for removal of water vapor from air is well known to the art. These materials have been utilized as desiccants and dehumidifying agents. The use of these agents as a method for producing a liquid solution for various end purposes has been explored briefly. For example, this method has been used in the self-sterilization of chemically oriented explosive mines. In the past, hygroscopic deliquescent materials have been incorporated into the explosive component in these mines to provide a non-mechanical method of sterilization, as described in U.S. Pat. No. 3,718,513. The mine design, of course, must allow for contact of the materials with water vapor in order for the method to function.
While incorporation of these materials into the explosive in the mine is an effective method of sterilization, it is not completely satisfactory, since a long accurately-timed period before sterilization cannot be attained. This limitation occurs because as the hygroscopic, deliquescent material absorbs enough water vapor it immediately begins to drip, therefore sterilization begins as soon as the mines are exposed to moist air. Additionally, longer periods of time before sterilization are impossible to attain, because of the relatively rapid dispersal of the solution throughout the mine.
It is, therefore, an object of this invention to provide a means for accurately controlling the time necessary for sterilization of chemically oriented mines, such controlling means functioning by the use of a desired hygroscopic element, external but exposed to the mine, that for a number of days will not discharge any solution which might impair the effectiveness of the mine, then after the desired number of days will discharge the solution at a relatively high rate.
A further object is to provide a means for controlling the rate and amount of sorption, liquefaction and solution release by a sorbing material in a fluid containing medium such as air containing water vapor.
Another object is to provide a control means to prevent indiscriminate solution release by a hygroscopic, deliquescent material.
Other objects and many of the attendant advantages of this invention will be readily appreciated as the same become better understood by reference to the following description wherein it is shown that the above-mentioned objects are attained and the prior art deficiencies are overcome by the use of an essentially water vapor-impermeable film packet enveloping the sorbing and solution-releasing material, such packet having a preselected number of perforations of a predetermined size, to accomplish these objects. The term "solution", wherever used herein, means "liquid solution".